


Illogical

by tloraxin



Series: FWB SenGen [1]
Category: Dr. STONE (Manga)
Genre: Alternate Universe - Modern Setting, But anyway it's our current world setting, Francoise too, M/M, Modern is not a good word, Nanami Ryusui is in this but he's not in characters tag, Not Beta Read
Language: English
Status: Completed
Published: 2019-09-14
Updated: 2019-09-14
Packaged: 2020-10-18 05:00:46
Rating: Explicit
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 4,342
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/20633480
Author URL: https://archiveofourown.org/users/tloraxin/pseuds/tloraxin
Summary: The logical thing would be to reject it altogether and never again associate himself with that man. But tonight was already as absurd as it could ever be, so what could hurt with one more illogical decision?------Sen/Gen smut I think everyone needs by now :^)





	Illogical

**Author's Note:**

> Basically I need Senku/Gen smut so much I'm writing it myself. This fic will be setting in our current world, Senku is going to uni, etc. Also, please note that there are maybe a lot of grammatical mistakes and made up words, since English is not my first language.  
\----  
I made sort of "companion" art first, to maybe let you imagine them in the current world fashion here >>> https://tloraxin.tumblr.com/post/187664322889/i-have-been-imagining-their-modern-world-story-but  
(Also could be considered as a shameless self blog promotion if you want...)  
\----  
And so... Please enjoy! :)

As if he needed to prove to everyone that Nanami’s family is _that_ rich, Ryusui actually booked this entire high class nightclub to celebrate his birthday’s after party tonight. The said guy was now on the stage, announcing about how everyone may order everything and it’s all free, prompting loud cheering of the invited guests.

Senku chuckled to his beer. That guy sure know how to party. Though, as expected, the one who’s arranging it all must be Francoise –who was currently sitting at the bar with their upright posture as usual, walkie talkie ready on their right hand.

“That’s all you’re going to order? A can of beer?” Chrome questioned him, one eyebrow raised, “It’s free for all night, Senku! Do I need to remind you?”

“I’m the one who need to remind you that tomorrow we need to be in the lab,” Senku replied with a scoff, “And I’m not going to cover your hangover ass to professor.”

Chrome looked a bit worried –but then Kohaku hurried to fill in the conversation, “No, Chrome! Do not let Senku get into your mind, geez!” She exclaimed, “We’re in the party right now, so we’re going to drink and we’re going to party and we’re going to dance until the morning comes!” She finished it off with gulping down the rest of her drink.

Senku just laughed. Chrome was Senku’s lab mate in the same final project for their major in Nanoscience, and Kohaku was Chrome’s childhood friend, studying Anthropology. She was in for sport scholarship, though, a former all time high school champion in track and field. Three of them bonded quite interesting friendship, and to Senku, they healed his loss of Taiju and Yuzuriha, his own childhood buddies. The couple decided to move away after high school to become farmers in some 3 hours away village from their town (They always sent Senku freshly harvested veggies from their garden to this days).

Kohaku cheered, “This is my favorite song! Chrome, let’s go dance!”

Even as Kohaku pulled him away from their seat, Chrome still looked uneasy. Senku sighed and laughed, “Just go. I can say you’re sick or something.”

Chrome grinned, “Thank you, Senku!” The pair walked away from their high table to join the rest group of their friends towards the crowded dance floor.

Chrome and Kohaku were invited to the party through Senku, who was in the student council with Ryusui, a student of marine engineering major, their year’s council president. Senku originally never intended to participate in any student activities, but Ryusui insisted for him to be his vice. They didn’t even know each other that time, but the latter had heard of Senku’s excellence in leading labs and handling projects, and immediately asked him in person. More than for the student council, Senku finally joined because he’s interested in Ryusui’s daring words and visions.

Senku was always pulled to people who were genuine and virtuous. Taiju was the most sincere and determinated person he ever met. Yuzuriha was diligent, honest and a natural hard-worker. Chrome’s pure excitement for science and discovery matched his own very well. And he adored Kohaku’s outright and straight-forward act, which most likely was rooted in her sportsmanship. Then Ryusui. In the world of science, being fake won’t get you anywhere.

Senku tapped his finger lightly. Now he couldn’t go home early, since he might need to bring Chrome home. Reading the rest of science journal he started two days ago on his Kindle in such loud place might be impossible, too. Absentmindedly, he looked around. It’s not just kids from their campus, but there’re several people Senku never recognized before.

He spotted some couple (or maybe just a pair of strangers) started making out already on the more comfortable sofa table. Senku looked away, then feeling dumb of doing so. His last relationship was over one years ago, and after that, he’s practically in the science lab every day. He couldn’t even remember the last time he kiss. But still, feeling up a stranger you never know before and ended up having sex that way was just utterly _illogical_. Not to mention, very risky. He’s not that desperate.

Just as he finished this thought, someone passed his table, and Senku suddenly caught a really nice scent. It’s flowery, sweet, but not the piercing, sickening one –this one was so soft, lingering lightly in the air. He could almost trace the smell, and his eyes landed in a guy, standing near to the dance floor, edging outside the dancing crowd.

The man was around his height. His hair was dyed in half and half bicolor silver and black, with uneven cut. His right side hair grown long until a bit passed his chin, while the rest of it looked like a normal boy’s cut. He’s talking to his friend, but then he shook his head about something and his friend left him to the dance floor. Senku couldn’t really make out his face, but he noticed how the pearl white skin was gleaming in purplish hue from disco light. The stranger was tall and slim–even a bit bony, almost, and adorned himself in loose floral shirt tucked in skinny fitted black jeans, tighten with matching color leather belt.

He got a slender and sleek heck of a neckline, which Senku found himself gulping down about. Senku finished the rest of his beer and left his table to approach that guy. Then it started fill his nose and head, the previous scent. What the heck is this smell? The closer he got, the more he drowned in the fragrance. It’s not like it’s very strong, or that it’s stinks –It’s really soft, but hypnotizing. It’s like… **_pheromone_**. Which was ridiculous, because human didn’t supposed to be radiating pheromone.

He stepped forward, and now his body almost bumping to the figure in front of him. His senses were blinded by the smell, somehow turning off a tinker on his brain. Senku found himself titled his head to nose on the curve of the neck, inhaling deeper. The guy in front of him jolted, but not looking back. Not even when Senku pressed their body even closer, and start to kiss around the exposed neck and shoulder. He felt the quickening pulse under his lips, now even quicker than the beat of music beaming in his ears.

“You smell so good,” Senku breathed out.

The guy in front of him let out a whimper.

“May I?”

Did people pay attention to _consent_ when they’re doing this? But Senku would want one, anyway. The guy shifted his head a bit, glancing at Senku from the corner of his eyes, before turned his head back to the front. Senku only manage to trace some of his face features under the dark ambience –sharp, slanted pair of eyes, and thin lips, and amazing jawline.

He nodded. Senku shuddered.

“Oh,” That man moaned, as Senku tried to experimentally grind forward to the tightly wrapped butt cheeks. Much to Senku’s excitement, the guy rolled his hips back. Isn’t this just great? Who the hell thought all of this was illogical earlier? It’s probably is still are, but right now it really doesn’t matter.

Senku’s aroused, and very much hot instantly. Hell, how long have it been since the last time he was touched _there_? Even with his own hand? Didn’t the last time he masturbate was three months ago? Damn, that was long. He’s sure forget about everything every time he stepped into the lab. He didn’t realize this much strain he put to his own body.

This guy in front of him was sure as heated–he flushed down in red to the tip of his ears. Senku set a hand to hold onto the stranger’s bony hips, while the other sneak under the unbuttoned –first to fourth, no… fifth –collar. The chest was warm, smooth and taut… and as thin –Senku’s fingertips felt the softly protruding ribcage immediately. Slowly, he caressed his way to stroke on the nipples, feeling it perking up under his thumb.

“Nn –no…” The guy’s breath hitched and he shuddered. Still not slapping Senku away –and Senku made sure that guy can just do it if he want to, he didn’t put that much force onto his grip. But just to confirm…

“No?”

“Uh, I mean…” He practically moaned his next words, and Senku felt his arousal just _grow, _“Haa –it’s fine. Please…”

“Ah… alright,” Senku processed to tease around the guy’s neck and shoulder part with his lips –and tongue too, actually, licking the sweat away and tasting bittersweet flavor of the skin. He then continued to the flushing ears, giving them slow stroke with his tongue and light nip on the tip with his teeth –while continued to play with the hardening nubs under his right palm. Senku was pinching them softly and stroking them lightly, actually really wanted to feel them inside his mouth.

That stranger was liking every part of it, he was squirming and mewling all time. People around seemed to give them some wider space, and two of them was probably quiet a spectacle right now, but who cares. Senku needed to touch more of this guy, smelled more of his dreamy scent and heard more of his cute little whimpers.

The guy whispered something. Senku was a bit dizzy of all the reawakened sensation, he didn’t quiet catch it, only managed to let out a small “Huh?”

Next thing he knew, his hand was quickly guided from the hip to the front fly of the stranger’s jeans –which was holding in a very hard and very much warm bulge.

“Gosh,” Senku breathed out. Oh, this is too much, “Fuck, I can do you right here right now,”

And to this, that guy finally turned his head back. Senku was blown away for a second or two, staring at the hot, sweating mess, flushed crimson face in front of him –the cat-like pair of warm grey pools eyes and thin, pink blushed lips which was shivering and just begging to be kissed onto senselessly, to his obvious jawline fitted to the sleek, long neckline… His exposed protruding collarbone and silky smooth pale chest with pinkish hue nipples just peeking away behind the light fabric, moving up and down fast with his ragged breath…

He _definitely_ can fuck this guy right here right now.

“L-let’s go,” The guy’s words was shaky, but his motion was not –he yanked Senku by his wrist quickly before he could actually reply, pulling him across the dance floor and what seems like a fast-rotating maze of alley until they ended up inside a cubicle of men’s toilet. It all happened in flash, he was slammed with his back to the door, then they’re kissing roughly –too much in heat to do it slow –teeth bumping and tongue twisting and they bite each other back, licking around the mouth and cheek and chin and along the jawline to the ear, sucking to the neck and any surface of seen skin trying to left marks and just taste each other more, and more, and more… Three months of any form of skin touching absence was actually worth this one’s amount of passionate, intense made out.

The guy’s hand grabbed around, taking Senku’s flannel off and pulling up his T-shirt pass his head, tossing them to the ground. He kissed further along Senku’s collarbone down to his chest, before then licking his way up to part of Senku’s shoulder near his neck, biting and sucking there. His right hand clenched tightly to the muscle of Senku’s back, and the other processed to knead around the latter’s arousal –which successfully gain him a breath hitch and a set of whimpers from Senku.

“God, you’re so good,” Senku breathed, reached out both his hand to cup on the pair of deliciously tight butt cheeks, before then moved his right leg to rub between the guy’s shaky limbs. This action immediately flattered with string of delightful moan by the beautiful stranger. He threw his pretty face up and just keep moaning, body twitching with lust, nipples perking up and protruding from behind the fabric –which Senku immediately reached onto, after tearing away the lower, still-buttoned part of the shirt (It’s not so much of cover up anyway in the first place) and yanked them completely open. He was rolling them between his fingers and pinching, making the owner pulsating even crazier, now drooling from the edge of his opened lips.

While making sure his knee was still kneading against the guy’s crotch, Senku pulled the small frame closer, wrapping his hand around to support now barely standing body. He mouthed the nub, teasing them with the tip of his tongue, then putting it between his teeth. Senku inhaled deeply to the chest –the sweet scent that attracting him in the first place filled his nose, and he felt like he tasted creamy sort of vanilla in his tongue.

“Ngh, nnh…” The guy squirmed. Senku looked up (His heart skipped a beat –in such close distance, the guys’s even more beautiful –his eyes was gleaming in pleasure tears and his lips were swollen and red –that guy was showing such lewd expression that it should be illegal), “Y-You’re going to come?”

“No, I –” That guy shook his head. His hand pushed Senku away gently, so Senku let him go. He’s confused, a bit scared that he crossed a line somehow (_where_?), but keeping his silence as he examined the guy stepped away from him. He turned his back to Senku, kneeled to the close-lidded toilet bowl and with shaky fingers, hastily unbuckled his pants.

Something clogged Senku’s throat –no, no, can it be? Is he _this_ lucky?

He is, apparently. That stranger pulled down his jeans along with his dark-colored briefs, displaying his bare bottom in front of Senku’s eyes –and didn’t just stop there, he reached back, kneading apart his butt cheeks to expose a twitching, pink hole. He titled his head back to Senku, “I want to come with you inside me...” He added, faintly, “Please?”

“I’ll be dead.” Maybe he said it out loud, or just in his head. But anyway –Senku quickly slipped away from his jeans, as fast as he could without tangling his own leg. He set himself behind the kneeling guy, and tried to probe a finger in –which _too much_ easily slipped in, even with his second and third fingers altogether.

“I-I’m ready, you know,” The guy whimpered, “I prepared it before I came here.”

It’s actually weird, but hell if it’s not even hotter. The guys gestured him a packet he fished out from the front pocket of his shirt–a condom.

Senku laughed between his breaths, “Fuck, you really want this.”

He propped his rubber wrapped dick, tried to tease the flinching muscle with the tip of it and feeling a shudder against him as a reply. He played around just bit more while adjusting his position, then slowly, surely… pushing in.

“Ah!” The guy sobbed out, “God, good God–” Senku moved his hips, the throbbing member sliding in and out with slick noises. The friction was too amazing… and even greater when suddenly that stranger clenched his opening tight. Senku’s breath hitched –“Oh, fuck,” He breathed, “Oh, fuck, you’re so good, really good.”

His ear was ringing, but he’s sure he heard a small chuckle. He wouldn’t last long –maybe just a minute or so passed but he could feel he’s peaking already. Senku slammed faster and harder, and the guy against him was moaning endlessly, mewling lewdly to his own palm.

Maybe he came first, or maybe that guy, but it’s not that much time apart. He never knew before that when you spurted out three months’ worth of come, it’s actually feel a bit like electrocuted, but with no pain. It’s really not a great analogy, but his head was in a mess. Senku heard himself groaned, and even after he came, he still cannot stop his hips until his knee finally gave in, and he ended up slumping to on top of his mating pal.

They took moments to adjust their breath. That guy also grew boneless, his cum puddling on the floor in front of him. Some several beats later and Senku realized he probably was crushing over the thinner guy, and jolted away with a “Sorry! Really sorry!”

The guy lied his head on top of the bowl lid, and smiled lazily to Senku, “It’s okay. I’m not that weak.”

Senku blushed a little. That guy’s afterglow was as beautiful. Senku leaned his back to the side wall of the cubicle, tying his condom while still trying to regain his composure. His head are even throbbing a bit, now.

“Can you still go?”

Senku blinked, “Huh?”

The guy turned to Senku and crawled closer, “Can you go another round?”

Senku replied with a gapping mouth. That guy’s face was now very close to his supposed-to-be-soft-dick that –much to his own shame –are now actually were hardening up again just by that question alone. That warm breath, shit! The guy tapped his finger on the tip –Senku flinched on this –and looked up to Senku.

“I can maybe help to make it hard again?”

Senku was lost at words, only manage to produce a string of whimper. He’s going to –oh, God, yes, he is going to– Senku moaned, witnessing the guy’s swollen lips gape apart to take his dick inside.

Senku clenched his toes. What the fuck, he never realized he’s such a pervert. Was he really just got hard again after releasing plentiful of cum inside someone else’s ass? But that guy –God, he’s so skillfull with his tongue. He’s swirling it around and playing with Senku’s tip, indulging it in his warm and moist cavity, fingers massaging the balls delicately with just right amount of pressure. He’s even daring enough to swallow even deeper until Senku’s tip hit the back of his throat –Senku was a bit worried about this, but it flied out of the window as that guy now move his wrapped lips up and down.

“You’re unbelievable,” Senku whispered. To this, the guy looked up and managed a smile. He continued until Senku stroked on his head, whimpering, “It’s good to go.” He released Senku’s dick with a pop, eyes glittering on the sight of back-to-alive-ride. The guy pulled Senku up –which Senku just wobbly obeyed –and pushed him gently to sit on the toilet seat.

It was quiet a haze afterwards, but Senku remembered the guy sat onto his lap and whispered on his ear: “It’s okay, you don’t have to do anything.” He plucked out another packet of condom from his pocket (How many of them that he got, really?) and putting it on Senku’s. Then he rolled his hip around a bit to settle their position, and finally slowly pushing Senku’s tip inside his still soft and gaping opening. The guy moaned, twitching as he crouched lower and his hole finally filled to the base of Senku’s cock. Senku let out a harsh breath to this, hands gripping on the side of that guy’s figure.

“Nnh, so full,” He sobbed out.

“You feel so good,” Senku added.

“I-I’m going to move.” The guy cried out, and started taking his time motioning his body up and down.

Senku groaned –his head was still pounding, and he seriously had trouble breathing, but this kind of slow friction just won’t do. He clenched his fingers tightly he’s sure he left bruises on those pale thighs, and pounding his hip upwards, faster. Harder, deeper.

If anyone actually decide to step inside the toilet now, they probably won’t, since the guy was now practically _screaming_ in pleasure, repeating the sentence like a prayer, “Oh, it’s so good! More, more!”

With the current so-called sitting arrangement, now Senku could really take a good look on the guy’s wrecked face. He’s embroidering it to his mind, which he think will be enough fap material for months to come: the reddening shade of the face, his eyes clouded with lust… his pleasure tears and sweat and heated breath Senku thought he can actually see him exhaling, torso now completely exposed (his shirt was long gone and Senku had no idea _when_) and how he’s flushed until just around his neck, the pair of pink nipples perking up to the arousal…

“You filled me so deep!” That guy cried out, “Nnh, I –I’m so close!”

“M-Me too,” Senku croaked out, “Clenched tight. Like before,”

That guy obeyed. Senku’s thrown his face up, overwhelmed by pleasure. He slammed his dick in and out vigorously, he almost forgot to breathe properly. The stranger came first, his body twitched like crazy as he spurted out his seeds onto Senku’s belly, and the pulsation made Senku came, too.

“Aaah…” That guys moaned, still shuddering. They’re so sticky and sweaty and Senku felt like he need immediate shower, but he’s too limp to even move. Senku rested his head on the guy’s shoulder, suddenly feeling super dizzy, like he got serious heatstroke.

“K-Kiss…”

Senku stammered, and looked up, “H-Huh?”

“Kiss me?” The guy asked softly. He framed Senku’s face with his hand to meet their lips together. Senku mewled to the kiss –this one was soft and slow, probably because they’re both too tired. But it felt so good, they pecked and pulled apart just to brush their lips again, over and over. Senku wrapped his arm around the guy, sighed. His pulsing forehead was slowing down… And, oh –that pretty stranger was stroking on his sweaty hair gently, and Senku felt _too_ comfortable about it.

“You’re flushed red,” His voice was so airy –this probably was not his normal speaking voice, but for now, it’s a music to Senku’s ringing ears, “Are you okay?”

Senku mumbled to the skin, “You were too the whole time,”

“I have almost no melanin,” The guy chuckled.

Senku inhaled, “You smells… so good,”

The guy kissed on his forehead (Oh damn, it felt so good…), whispered, “It was really great, thank you,”

“For me too, y’know.” Senku yawned. He couldn’t feel his body…

***

Senku opened his eyes so abruptly he felt another pang to his head –which luckily quickly go away. He blinked several times –he’s still in club, and was resting on… a sofa? He saw some other pile of human on the other side of the seat, snoring or totally wasted. The club has cleared out a bit, but the music was still on, some people still gathered here and there across the dance floor.

Senku patted around his body and found out he’s fully clothed. For a second he thought he just had a very naughty dream, but then his eyes caught the stranger –_i-in his dream…? Or not?_

The stranger giggled from his position across Senku, “You finally awake,”

“D-Did you? Clothed me?” Senku raised up his back. He accepted a bottle of water from the guy in front of him.

“You didn’t remember? You very sleepily put it by yourself. It was quite cute.” He giggled again. It sounds sickeningly _too_ sweet, and Senku didn’t know why he didn’t catch it earlier. Then he remembered it because all he heard from this guy before were moans.

“Then I brought you here by myself, you know! You’re quite heavy too. You should be thankful to me, no~?” The guy bounced his way to beside Senku, and leaning forward to bring their face close.

To this, Senku tried to remind himself again why he was so attracted to him before –maybe because he didn’t hear this guy talk. He added sort of swaying tone to his sentence which clearly was made up, and such fake pitch, too.

“Thank you,” Senku answered stiffly. Well the sex is as good as it was, but in normal situation, he’s clearly not someone Senku will deliberately prefer to connect to or anything. That guy for sure acknowledge the ice in Senku’s words, and he pulled back a little. He kept a smile on his face though, and shrugged, “Such a shame~ I thought we can totally get along, but seems like it’s not the case…”

Senku replied nothing to this. That guy shifted his head closer again, and whispered to Senku’s ears, “But the sex was good, right~? My dear stranger~?”

This time, Senku’s nose caught the earlier smell. Right, this is how they ended up doing it. How come it was so endearing? It’s _still_ so endearing, even with all these turn-offs. It made all the pleasures floated back to his memories. Hell, the sex wasn’t actually just good, it’s heavenly. Senku stared back to the guy’s eyes, “I guess. It’s the best in a while, indeed.”

“It is to for me, you know~” The stranger let out an exaggerating desperate sigh which Senku decided to just ignore. He then titled his head, asking sweetly, “Then… want to do it again?” He added, “We do not even have to talk, you know.”

The logical thing would be to reject it altogether and never again associate himself with that man. But the memories –flashes of aroused expressions and lewd frictions, sweat and sperm he still felt sticking to his clothes… That blowjob! And their somehow matching chemistry and vigorous energy…

Well, tonight was already as absurd as it could ever be, so what could hurt with one more illogical decision?

“Sure.” Senku crooked a grin, “You may moan, though.”

“Aw, how crude~” The stranger’s smile grew even wider, “Well then, let’s exchange our contact… Oh, and how silly, we didn’t even know each other name!”

Senku really tried to overlook this person’s antics, but it’s just so hard to do so when it’s right under his nose. He sighed, and answered, “I’m Ishigami Senku.”

“Oh, Senku-chan~!” That guy practically sing his name, “Then, it’s nice to meet you…"

"My name is Asagiri Gen!”

**Author's Note:**

> So basically this will be the beginning of tale of Senku and Gen as FWB, lol. The continuation is already a draft by now but I need to adjust with my work schedule, I hope it'll be soon!
> 
> I hope you enjoy reading it like I enjoyed making it. If you do, leave some comments, won't you? ;)


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